Immigration is a very complicated policy area and many aspiring presidents like Marco Rubio have an incentive to make it more so. The reason is that they are caught between the need to make primary voter appeals to their party's base and the need to not disqualify themselves in the eyes of the more general electorate.

In addition to this issue, Rubio must also deal with the consequences of his disastrous political mistake of lending his name to and allowing himself to be used as a poster boy for the purposefully massive and thus indecipherable Senate immigration bill that ignored long-standing public sentiment.

The host, Chuck Todd, set the stage for the taped interview as follows: "So last night I began by asking Rubio whether he wasn't also guilty of changing his positions many times, particularly on immigration." Rubio responded, reasonably enough, "If circumstances change or you learn something along the way, it's reasonable to say, 'Maybe a different approach will work better.'"

And then the trouble began (emphasis added):

CHUCK TODD: Let me ask you by the way quickly on the 11 million, are you still for finding a way for them to legally stay in the United States?

MARCO RUBIO: Yeah, look. If you're a criminal alien, no, you can't stay. If you're someone that hasn't been here for a very long time, you can't stay.

CHUCK TODD: Wait a minute. Define criminal alien--

MARCO RUBIO: I do believe we have to have a reasonable solution--

CHUCK TODD: De-- define criminal alien. Isn't anybody who's here--

MARCO RUBIO: A felon. A felon--

CHUCK TODD: Okay, so not-- 'cause some people argue--

MARCO RUBIO: Well I know some people have said that before but I believe--

CHUCK TODD: Okay, all right--

MARCO RUBIO: --the opposite. But-- no, but I've said that before, Todd. That's been convinced [sic? Convicted?]. I mean, a felon, someone who's committed a crime, a non-immigration-related-- and that's what I've talked about in the past. So I do believe-- I don't think you're gonna round up and deport 12 million people. Here's what I've said, though. It is very clear now more than ever that we are not going to be able to do anything on people that are illegally until we first prove to people that illegal immigration is under control and America is safe. And ISIS poses a very unique threat unlike anything we have faced in the past.

I've included the whole exchange to give a sense not only of its context, but also of how difficult it is to get a straight answer to a direct question.

Rubio starts out with his toughest stance: "If you're a criminal alien, no, you can't stay." Of course, to paraphrase Bill Clinton, it depends what you mean by "criminal alien". Todd asks precisely that question and begins by asking "Isn't anybody who's here ...", but he never got to finish that thought before Rubio cut off its obvious conclusion that any illegal alien could be considered to have broken the law and is thus criminal.

"A felon. A felon--", Rubio insists, and then goes on to clarify, "but I've said that before, Todd. That's been convinced [sic? Convicted?] ... I mean, a felon, someone who's committed a crime, a non-immigration-related-- and that's what I've talked about in the past."

This muddled answer either reflects a deliberate strategy or a lack of immigration knowledge on the senator's part that would be surprising at this late date.

Clearly missing is any mention of misdemeanors, some of which can be quite serious violations of the law. The Obama administration limited the consideration of misdemeanor charges in deportation proceedings to three separate charges. Rubio's answer provides no minimum or maximum number. It is also not clear whether the felony has to have been "committed", the word Rubio uses, or the alien "convicted of", which he may have also said but was mistranslated as "convinced". "Convicted" requires an official judicial determination, "committed" suggests simply being charged with a crime. And how would he count felony charges pleaded down to a misdemeanors?

It may be unfair to ask the senator to explain his position on all of the questions I've raised in the context of fast-moving interview.

Yet Rubio's answer leaves the impression that he has still not acquainted himself with the important details of the immigration debate. He seems content to stand on general terms like "criminal aliens" without showing that he knows the range of things that term might mean, and informing the public of his views on those important matters.

Perhaps he does have views, but is afraid to express them. Or perhaps, even at this late date, he has not yet had the time to think them through in his own mind.

The Center for Immigration Studies is an independent, non-partisan, non-profit research organization founded in 1985. It is the nation's only think tank devoted exclusively to research and policy analysis of the economic, social, demographic, fiscal, and other impacts of immigration on the United States.